quad crash video....question

I was running a camera mount test today. During my descent the motors were running but I lost the ability to slow the descent when I added power. There was some instability. I hit a tree and fell through the branches suffering 3 broken props and shearing my camera mount hold down screws (nylon). My battery pack is a hyperion 3s 4000mah Generation 2 and I still had over 40% left in the pack. Post crash I found 1 loosened prop nut. Not sure if that happened before ,during or after the crash. I am running gemfan 9x4.7 balanced props. Any ideas on the cause of the crash? Thanks.

Looks like you may have lost orientation for a second, that combined with the vibrations could have led to the crash. Personally, I never make a second flight on the same battery pack for the simple reason I don't know exactly how much time I have left to fly saftely. If you say you had 40% left after the crash and you only flew 2.08 minutes this must have been a second flight? Try better props to get rid of the Jello effect and balance the motors as well, they are notoriously out of balance.

Looks like it wanted to fall to the right. Could be if the prop nut came loose on that side of the copter it couldn't produce lift, or was producing much less lift from that motor so it drifted/fell that direction.

Looks like you may have lost orientation for a second, that combined with the vibrations could have led to the crash. Personally, I never make a second flight on the same battery pack for the simple reason I don't know exactly how much time I have left to fly saftely. If you say you had 40% left after the crash and you only flew 2.08 minutes this must have been a second flight? Try better props to get rid of the Jello effect and balance the motors as well, they are notoriously out of balance.

It wasn't an orientation issue. I was flying tail in in att mode. I fly helis also. Pretty hard to have an orientation problem with an auto stabilizing craft. I agree with charging after every flight. It only took 1700 mah to recharge and included a 5 minute test flight and the actual video flight. I believe the battery wasn't the cause. The issue was settling. I think one prop started to loosen resulting in loss of lift. More tests to follow. How are you balancing your motors? My props were perfectly balanced and in hover there were no visible vibrations at all.

I might be wrong

Quote:

Originally Posted by bladeaudio

Looks like it wanted to fall to the right. Could be if the prop nut came loose on that side of the copter it couldn't produce lift, or was producing much less lift from that motor so it drifted/fell that direction.

I was flying nose in and it was the left front prop that was loose after landing. That would have accounted for the loss of lift AND may have also been an orientation issue. I mounted the camera backwards on the vehicle for this flight, the wind was from left to right. As it drifted towards the trees I may have corrected in the wrong direction thinking I was tail in. That doesn't account for the loss of lift. I think a loose prop was the cause and I may have made it worse.

I put on some 9x5 zingers afterwards and it's flying fine again.

I may attach the yellow fin again to help with orientation.

Images

EDIT** You just posted you were actually nose in which I was typing... that changes a lot of my post. Still check around the hub of the prop to see if there is wear from the motor spinning on it. Also... good luck figuring out my post now!
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Sorry to hear about your spill!

Watched your video over and over and it's honestly hard to tell. If your camera is mounted towards the nose (nice take off nose in BTW if you do have it pointed forwards) then I would assume an issue with your front right motor. If that was the loose prop nut then that's where my money lies, check the hub around the prop for signs of wear because the motor was out-spinning it and it sometimes leaves marks. Also recheck all your solders and make sure they all look good. A cold solder has lead to the death of MANY multis.

You sound very experienced but it could have been loss of control if your gains aren't right and you were dealing with wind. I heard a lot of wind noise once you cleared the top of the houses, was it windy or was that all prop wash? The reason I say that is because gains being too sluggish can often times make it fly odd when going from a high wind to a low wind situation. On the ground in 5mph winds my F550 can be rock solid but up in the air 100+ feet in 15-20mph it acts very different. I learned early that once I get near the tops of the trees (20-30ft) that I need to slow my decent because once I get back out of the wind I will drop much faster. I don't know if it's lift, if I give it more throttle in the wind when flying, or something else but it's something I have to do when descending now. Actually now I adjust my gains when I get up high and adjust them back when I get lower to the ground, just smooths things out and makes everything more predictable.

EDIT** You just posted you were actually nose in which I was typing... that changes a lot of my post. Still check around the hub of the prop to see if there is wear from the motor spinning on it. Also... good luck figuring out my post now!
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Sorry to hear about your spill!

Watched your video over and over and it's honestly hard to tell. If your camera is mounted towards the nose (nice take off nose in BTW if you do have it pointed forwards) then I would assume an issue with your front right motor. If that was the loose prop nut then that's where my money lies, check the hub around the prop for signs of wear because the motor was out-spinning it and it sometimes leaves marks. Also recheck all your solders and make sure they all look good. A cold solder has lead to the death of MANY multis.

You sound very experienced but it could have been loss of control if your gains aren't right and you were dealing with wind. I heard a lot of wind noise once you cleared the top of the houses, was it windy or was that all prop wash? The reason I say that is because gains being too sluggish can often times make it fly odd when going from a high wind to a low wind situation. On the ground in 5mph winds my F550 can be rock solid but up in the air 100+ feet in 15-20mph it acts very different. I learned early that once I get near the tops of the trees (20-30ft) that I need to slow my decent because once I get back out of the wind I will drop much faster. I don't know if it's lift, if I give it more throttle in the wind when flying, or something else but it's something I have to do when descending now. Actually now I adjust my gains when I get up high and adjust them back when I get lower to the ground, just smooths things out and makes everything more predictable.

Good luck with your investigation!

I have not set my gains on the xmtr yet so it makes things more difficult in varying wind. It was fairly calm at take off but I'm sure it picked up at altitude.

You have two things going concerning loss of lift. More wind equals more lift due to translational lift being generated as the wind passes the tops of the rotors, requiring less power (throttle). Also, while descending, especially in no wind it is sometimes helpful to move forward a bit rather than fall through the rotor wash (which can increase the rate of descent).

Gains

You have two things going concerning loss of lift. More wind equals more lift due to translational lift being generated as the wind passes the tops of the rotors, requiring less power (throttle). Also, while descending, especially in no wind it is sometimes helpful to move forward a bit rather than fall through the rotor wash (which can increase the rate of descent).

Which led's are you using and how are you powering them? Thanks

I knew about the dirty air while descending but wasn't aware of the transitional lift. Cool!

LEDs ... well I have a few different kinds and use none. My orientation is simplified by flying only FPV now. When flying LOS I used THIS in the front and THIS along with my VU in the rear. They are super bright and helped determine which direction I was heading. If I lost orientation I just stopped and rotated to see which way I was facing . I have also purchased a few different colors of THIS but never hooked them up aside from to see how bright they were. Daylight makes all LEDs work less but as long as you aren't hundreds of feet away or into the sun they help.

The first two lights I plugged directly into my RX and I have heard of people running the strips directly from 3s batteries.

I'd like to know some good settings for gains which might work well in some wind on my F450.

Every craft is different. I have seen dozens of people try to use someone elses gain settings only to get pissed because their "Naza is broken" because they don't work! Gains will change with props, battery, weight, frame, conditions and i'm sure even altitude above sea level.

This leads to one of my favorite parts of the hobby... TESTING!

EDIT** Setting up sliders/knobs on your TX makes it MUCH easier. It sucks having to go inside/home, plugging it in, adjusting a couple numbers, then going back out to fly for 1 minute. BTW once you adjust the slider/knob on your TX after flying on a windy day, plug in your Naza and write down the settings. Then on the next windy day you know where to set your gains before leaving the house! (zero your slider/knobs when you do this....)

I knew about the dirty air while descending but wasn't aware of the transitional lift. Cool!

LEDs ... well I have a few different kinds and use none. My orientation is simplified by flying only FPV now. When flying LOS I used THIS in the front and THIS along with my VU in the rear. They are super bright and helped determine which direction I was heading. If I lost orientation I just stopped and rotated to see which way I was facing . I have also purchased a few different colors of THIS but never hooked them up aside from to see how bright they were. Daylight makes all LEDs work less but as long as you aren't hundreds of feet away or into the sun they help.

The first two lights I plugged directly into my RX and I have heard of people running the strips directly from 3s batteries.